<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title> </title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .top {
            height: 100px;
            width: 100%;
            background-color: red;
            position: fixed;
            left: 0;
            top: 0;
        }
.left{
    position: fixed;
    left: 0;
    top: 0;
    background-color: red;
    width: 200px;
    height: 100%;
}

        body {
            padding-top: 150px;
        }

        h1 {
            height: 1000px;
        }
    </style>
</head>

<body>
    <div class="left">导航条</div>
    <h1>内容区域</h1>
</body>

</html>